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Sweep 28 Aug 2026 · 00:00Z Build v2.1.250 478 read Stable v2.1.236 Latest v2.1.250 Next v2.1.250 Feeds RSS JSON llms.txt

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

Reference / Feature flags

tengu_amber_lark

A Claude Code feature flag, read out of the shipped bundle. It was in the build from v2.1.138 and was gone by v2.1.242.

What it is

Nobody has written a line about this one. It is not in any of Anthropic's reference tables and no changelog entry here carries a description of it. It is in the build, which is the whole of what this page can claim.

Presence across releases

ReleasesReadingDeclared typeDefault
2.1.245 – 2.1.250 5 releases never mined — —
2.1.242 – 2.1.243 2 releases not in the build — —
2.1.138 – 2.1.241 93 releases in the build — bool:false

A row reading never mined is a release with no archived bundle behind it. Nothing was read out of it, so nothing here says whether the name was in it. A declared type or a default is only ever what that release's own bundle stated.

Gate readings

No release here has a gate table behind it for this flag. Most published releases have none at all: the readings exist only for versions the pipeline captured flag state on.

Changelog entries naming it

No changelog entry here has ever named it. That is a statement about what has been written, not about the name: it has been in the build since v2.1.138 without anybody writing a line about it.

Documentation pages

None of Anthropic's documentation pages this site has a copy of carries this name.

Names beside it

Every feature flag in the inventory starting tengu_amber, up to twelve of them.

tengu_amber_anchorNo description from anybody. 2.1.138 tengu_amber_astrolabeNo description from anybody. never mined tengu_amber_creekAccepting fullscreen now runs as a trial, and two crashed launches disable it on that machine. 2.1.138 tengu_amber_flintNo description from anybody. 2.1.138 tengu_amber_heronNo description from anybody. 2.1.186 tengu_amber_kestrelNo description from anybody. 2.1.217 tengu_amber_latticeNo description from anybody. 2.1.144 tengu_amber_lynxNo description from anybody. 2.1.138 tengu_amber_moleskinNo description from anybody. 2.1.179 tengu_amber_packetNo description from anybody. 2.1.198 tengu_amber_prismNo description from anybody. 2.1.138 tengu_amber_quartzNo description from anybody. never mined

Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the feature flag does. All feature flags.